Download of OpenNap for OSX 0.4 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free Mac app was originally designed by Fork Networking. OpenNap for OSX for Mac relates to System Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
OpenNap is a program that allows you to create your own Napster servers, for peer-to-peer network working and file sharing.
You may want to check out more Mac applications, such as MPlayer OSX Extended, nrf-ble-sniffer-osx or QuickShow OSX, which might be similar to OpenNap for OSX.